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Lab test

Diphtheria Antitoxoid Test

The diphtheria antitoxoid test measures antibody levels in a serum sample. Quest describes it as a way to evaluate a person's immunization response to diphtheria.

Blood drawQuest patient service center

About this test

Diphtheria antitoxoid antibodies develop in response to diphtheria immunization or exposure. This test measures their level in a serum sample using an immunoassay method, giving a picture of a person's immune response related to diphtheria.

Quest lists this product under names including DPT Titer and Anti Diphtheria, reflecting its use in checking immunization status rather than diagnosing active infection. As with other single antibody titers, the result is one data point that a clinician places alongside a person's vaccination history and any relevant symptoms, rather than a stand-alone verdict on immunity.

Who might consider this test?

  • Usually looking to evaluate their immunization response to diphtheria
  • For example before travel
  • For occupational requirements

Test details

Quest code4865
MethodologyImmunoassay
Sample type1 mL serum
CollectionQuest patient service center

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Quest resources

Additional details

What this test looks at

The test reports the level of diphtheria antitoxoid antibody in a serum sample, measured using immunoassay. Quest also lists it as DPT Titer and Anti Diphtheria.

Order online and a physician order is included — no doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.

Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.

Frequently asked questions

What does this test measure?

It measures the level of diphtheria antitoxoid antibody in a serum sample, using an immunoassay method.

How is the sample collected?

The test uses a serum sample from a routine blood draw at a Quest Diagnostics patient service center.

Do I need to prepare for this test?

No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides.

What is this test used to evaluate?

Quest describes it as a way to evaluate a person's immunization response to diphtheria.

Is this the same as a diphtheria vaccine?

No. This is a blood test that measures antibody levels; it does not provide immunization itself.

How much is a Diphtheria Antitoxoid test?

$85, paid once at checkout. The price includes the physician's order this test requires and sample collection at a Quest patient service center.

Last updated 2026-09-18 · How we write about lab testing

Educational content

This page is for general educational purposes only. It is not medical advice, and it is not a substitute for consultation with a qualified healthcare professional. Laboratory results should always be interpreted by a licensed clinician who knows your health history. If you have questions about your health or your results, talk with your doctor. If you think you may be experiencing a medical emergency, call 911.